Question

我正在使用带有UI组件的dll，根据MSDN文档，我们需要显式注销在dll中注册的窗口类。（与在非dll进程中注册时，系统会自动将其注销）不同。

现在的问题是，在DLL_PROCESS_DETACH函数的DllMain消息中，我们可以知道进程何时卸载dll或它是否终止，但是如何确定dll是否即将从内存中完全卸载？

因为在每个进程分离中取消注册窗口类的时间都不合适，因为其他窗口可能仍在使用注册的类。

一旦没有其他进程在“使用”该dll，我想注销所有类。似乎是执行此操作的正确时间。

这是我现在注销所有课程的方式：

BOOL APIENTRY DllMain(
    HMODULE hModule,
    DWORD  ul_reason_for_call,
    [[maybe_unused]] LPVOID lpReserved) noexcept
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
        break;

    case DLL_PROCESS_DETACH:
        /*
        * Note As it turns out, HMODULEs and HINSTANCEs are exactly the same thing. 
        * If the documentation for a function indicates that an HMODULE is required, you can pass an HINSTANCE and vice versa.
        * There are two data types because in 16-bit Windows HMODULEs and HINSTANCEs identified different things
        */

        // static method call to Unregister all window classes
        wsl::ui::ClassAtoms::UnregisterClassAtoms(hModule);
        break;
    }

    return TRUE;
}

这是实现，如果您好奇的话，但这并不重要。

namespace wsl::ui
{
    class ClassAtoms
    {
    public:
        static void AddClassAtom(const ATOM& atom)
        {
            mAtoms.push_back(atom);
        }

        static void UnregisterClassAtom(const ATOM& atom, const HINSTANCE& hInstance)
        {
            // If the class could not be found or if a window still exists
            // that was created with the class, the return value is zero.
            if (!UnregisterClass(MAKEINTATOM(atom), hInstance))
            {
                ShowError(ERR_BOILER);
            }
        }

        static void UnregisterClassAtoms(const HINSTANCE& hInstance)
        {
            for (auto& ref : mAtoms)
            {
                UnregisterClassAtom(ref, hInstance);
            }

            mAtoms.clear();
        }

    private:
        inline static std::vector<ATOM> mAtoms = {};

        // deleted
        ClassAtoms() = delete;
        ~ClassAtoms() = delete;
        ClassAtoms(const ClassAtoms&) = delete;
        ClassAtoms(ClassAtoms&&) = delete;
        ClassAtoms& operator=(const ClassAtoms&) = delete;
        ClassAtoms& operator=(ClassAtoms&&) = delete;
    };
}

确定DLL_PROCESS_DETACH是否为最后一个

0 个答案: